The Correlation between Anti GAD65 Antibody and Autoimmune Encephalitis with Seizures Responding to IVIG and Rituximab: A Case Report

This case report discusses the clinical presentation, diagnostic challenges and management of a 24-year-old male with anti-GAD65 encephalitis. The report highlights the importance of early diagnosis and treatment to ensure a favourable outcome. The glutamic acid decarboxylase 65-kilodalton isoform (GAD65) antibody is a biomarker of autoimmune central nervous system (CNS) disorders and, more commonly, non-neurological autoimmune diseases. Type 1 diabetes, autoimmune thyroid disease, and pernicious anaemia are the most frequent GAD65 autoimmune associations. One or more of these disorders coexists in approximately 70% of patients with GAD65 neurological autoimmunity. Neurological phenotypes have central nervous system (CNS) localization and include limbic encephalitis, epilepsy, cerebellar ataxia, and stiff-person syndrome (SPS), among others. Timely initiation of appropriate therapy can avoid serious complications in the patient. Therefore, high clinical suspicion should be there if the initial workup doesn’t lead to a diagnosis.